Along with Pine Island Glacier, Thwaites Glacier has been described as part of the "weak underbelly" of the West Antarctic Ice Sheet, due to its apparent vulnerability to significant retreat. This hypothesis is based on both theoretical studies of the stability of marine ice sheets and recent observations of large changes on both of these glaciers. In recent years, the flow of both of these glaciers have accelerated, their surfaces lowered, and the grounding lines retreated.

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In 2011, using geophysical data collected from flights over Thwaites Glacier (data collected under NASA's Ice Bridge campaign), a study by scientists at Columbia University’s Lamont-Doherty Earth Observatory showed a rock feature, a ridge 700 meters tall that helps anchor the glacier and helped slow the glacier's slide into the sea. The study also confirmed the importance of seafloor topography in predicting how the glacier will behave in the near future.[5] However, the glacier has been considered to be the biggest threat on relevant time scales, for rising seas, current studies aim to better quanitfy retreat and possible impacts.[6]

Swamp-like canal areas and streams underlie the glacier. The upstream swamp canals feed streams with dry areas between the streams which retard flow of the glacier. Due to this friction the glacier is considered stable in the short term.[7]

A University of Washington study, using satellite measurements and computer models, determined that the Thwaites Glacier will gradually melt, leading to an irreversible collapse over the next 200 to 1000 years.[8][9][10][11][12]

On 15 March 2002, the National Ice Center reported that an iceberg named B-22 broke off from the ice tongue. This iceberg was about 85 km long by 65 km wide, with a total area of some 5,490 km². As of 2003, B-22 had broken into five pieces, with B-22A still in the vicinity of the tongue, while the other smaller pieces had drifted farther west.

The Thwaites Iceberg Tongue (74°0′S108°30′W﻿ / ﻿74.000°S 108.500°W﻿ / -74.000; -108.500) was a large iceberg tongue which was aground in the Amundsen Sea, about 32 km northeast of Bear Peninsula. The feature was about 112 km long and 32 km wide, and in January 1966 its southern extent was only 5 km north of Thwaites Glacier Tongue. It consisted of icebergs which had broken off from the Thwaites Ice Tongue and ran aground, and should not be confused with the latter, which is still attached to the grounded ice. It was delineated by the USGS from aerial photographs collected during Operation Highjump and Operation Deepfreeze.[13] It was first noted in the 1930s, but finally detached from the ice tongue and broke up in the late 1980s.[14][15]